Device for cutting an inductive resistance out of circuit without sparking



July 29 1924. 1,503,376

' J. PFRETZSCHNER DEVICE FOR CUTTING AN INDUCTIVE RESISTANCE OUT OF CIRCUIT WITHOUT SPARKING Filed Sent. 26. 1921 Patented July 29, 1924.

UNITED STATES 1,503,376 PATENT OFFICE.

J'AKOB PFRETZSCHNER, OF ESSEN, GERMANY, ASSIGNOR T FRIED. KRUPP TI-EN. GES ELLSCHAFT, OF ESSEN-ON-THE-RUHR, GERMANY.

DEVICE FOR CUTTING AN INDUCTIVE RESISTANCE OUT OF CIRCUIT WITHOUT SPARRING. Q

Application filed September 26, 1921. Serial No. 503,251.

To all whom it may concern: I

Be it known that I, JAKOB Prnn'rz- SCHNER, residing at Essen, Germany, a citizen of the German Republic, have invented a certain new and useful Improvement in Devices for Cutting an Inductive Resistance Out of Circuit Without Sparking, of

which the following is a specification.

This invention relates to a device for outting an inductive resistance out of circuit without sparking. Devices of this kind are described, for example, in application Ser. No. 437,888. This prior device is based upon the idea of connecting an auxiliary resistance in parallel to the inductive resistance, to actuate an automatic circuit breaker, connected in series with the inductive resistance.

Now the object of the present invention is to provide a device of this kind which, in comparison with the subject-matter of the above patent application is distinguished in particular by a still simpler manner of manipulation and greater reliability of work- 1n The invention will be described with reference to the accompanying drawing which shows diagrammatically an example embodying the subject-matter of the invention.

The inductive resistance A which is to be switched oil", and which is formed, by way of example, by the winding of a magnet wound around an iron core, is connected in series to the gap contacts 6 and b of an automatic switch B, and also to the magnet winding (1 of a switch D which can be switched on by hand. The magnet winding al is provided for the purpose of holding the switch D, when switched on, in the on position against the action of a tension spring d as long as a current flows through the inductive resistance A. It is not however capable of bringing the switch D into the on position. The switch D is provided with two contacting elements d and d.

When the switch D is in its on position, the contact element 01 bridges over a gap between the two switch contacts d and d and provided in a conductor 0 which contains an auxiliary resistance C. This conductor a is connected in arallel to the inductive resistance A an the ma et winding d? in series therewith. At the same time the contact element d bridges over a gap in a conductor E which is connected to the poles of a source of continuous current supplying the inductive resistance and contains the magnet winding 2) of the automatic switch B already mentioned.

The switch B is provided with a pressure spring 6, acting in opposition to the magnet winding b and has, in addition to a contact element b intended to [bridge over the gap 72 b in the main circuit two other contact elements b and b which serve to brldge over gaps in each of two conductors F and G when the main circuit is opened by the switch B.

The conductor F, which contains the gap f i adapted to be bridged over by the contact element 6 is connected at one end to the positive pole of the source of current andat the other end to the switch block b of the switch B. The conductor F also includes an auxiliary resistance 7. A second auxiliary resistance 9 is placed in series with the conductor G, which contains the gap g 9 adapted to be bridged over by the contact element b and is connected at one end to the negative pole of the source of current and at the other end to that end of the magnet winding d of the switch D which is remote from the inductive resisttime A.

In the conductor G is placed in addition to the gap previously mentioned, a second gap bounded by two switch blocks 9 and g and adapted to be bridged over by the contact element k of a switch H, arranged for two switch positions and operated by hand.

This switch H has a winding h lying in the main current circuit, and a gap which is bounded by two switch blocks h and h which are connected in series with the magnet winding d of the switch D, the incluctive resistance A and the gap 6 b of the switch .B. The purpose of the magnet winding k is to hold the switch H, against the action of a tension spring h, in that switch position in which the gap 71. h is bridged over by the contact element h until the main current circuit containing the inductive resistance A and the magnet winding 75, has become devoid of current.

For thetwo switches D and H which are to be operated by hand, there is provided over into the on position, the respective tension spring being tensioned. A fiat spring 2' mounted on the operatlng lever J causes the latter to always return to its central position I as soon as it is released.

The description of the working of the above described arrangement will be commenced from the position shown in the drawing, in which position all parts of the device, and in particular therefore also the inductive resistance A, are without current and the operating lever J is in its central position (I).

Supposing the inductive resistance A is now to be switched on, the operating lever J is moved over into position II and then net windings d and 7L2.

ment (3.

released so that it returns to position I under the action of the flat spring i At the same time the switch vH is brought into the position in which the contact element it bridges over the gap k k even after the 7 return of the operating lever J to its central position marked I.

On the other hand the magnet winding 03 is unable to move the switch D into its 5on position as the reluctance of the magnetic circuit of the switch D, when in the off position, is too great for it to do so.

Supposing now the inductive resistance A is to be switched off, the operating lever J is moved over into the position marked III and released. The switch D then passes into the position, in which the contact element (i bridges over the gap 07 d and at the same time the conductor E containing the magnet winding 6 of the automatic switch B is closed by the contact ele- The bridging over of the gap 03 03 connects up the auxiliary resistance C in parallel with the inductive resistance A and with the magnet winding al connected up in series with the latter. In consequence of the excitation of the magnet winding 6 the switch B is switched off against the actionof the spring 19 which latter is now compressed and the'contact element 6 is displaced from inductive resistance A is switched off from the source of current. Notwithstanding no sparking occurs at the gap 7) 77 because the circuit A c C (1 d a? c al A presents a closed path to the induction current produced on the breaking of the circuit. As long as the induction current which flows through the inductive resistance A in the same direction in which the main current previously did, still possesses any appr'ciable strength, the switch D is held in the on position by the magnet winding (1.

At the moment of the breaking of the main current circuit by the switch B the magnet winding k is also deprived of current, so that the switch H returns to its position shown in the drawing, under the action of the tension spring h. In this position the contact'element k bridges over the {one gap 9 g still left open in the conductor G so that a current flows for a short time in the circuit F f f I) f A J G g h g G g g b g G E which passes through the inductive resistance A in the opposite direction to that of the induction current and of the main current precedingit. The magnetism which may still exist in the iron core of the inductive resistance A including'the residual magnetism can thereby be effectually destroyed.

As soon as the induction current in the circuit A 0 C (Z 11 d c d A has died down and the residual magnetism in the inductive resistance A has been destroyed the switch D, which is no longer held by the magnet wmding (1 returns under the action of the tension spring at to its off position shown in the drawing. This causes the conductor 0 containing the auxiliary resistance C to be interrupted, while on the other hand the conductor E with the magnet winding 6*, becomes deprived of current so that the automatic switch B also returns to the position shown in the drawing, under the action of the pressure spring I). Then the auxiliary resistances f and g are also switched ofl from the source of current and the inductive resistance A and the device is once more ready for use.

The simple manner of manipulation and the great reliability of working brought about thereby is based upon the fact that the present device can be specially well combined with a switch device J i which while being free from all possibility of being wrongly manipulated, permits of the con nection, by one switch movement, firstly of the inductive resistance A and secondly, by

a second switch .movement, of the magnet winding 6 of the automatic switch B, to the source of current.

A further advantage of the hereinabove described device consists in the fact that the points of connection of the conductors F and G which supply the demagnetizing current are formed by the switch blocks 12 and 12., so that only the'ends of the inductive resistance need to be accessible, while a third connection in the middle of the inductive resistance lieretoforedisclosed is superfluous.

The arrangement of two auxiliary resist ances f and g which can be connected up in series, instead of only one such resistance ofl'ers finally the advantage that short-circuits across the conductors F and G can be effectually avoided even in the case that a spark produced on switching off remains between I) and b b or between H and h h.

Claims:

1. In combination with an inductive resistance connected in a main circuit, a resistance element connected in shunt with said inductive resistance, a switch in said shunt circuit, an electro-magnetically controlled switch in said main circuit, means for exciting the windings of said electro-magnetically controlled switch from said main circuit, a switch for controlling said excitation and common means for controlling said last named switch and said shunt circuit switch whereby they being closed, said main circuit switch is opened.

2. In combination with an inductive resistance connected in a main circuit, a resistance element connected in shunt with said inductive resistance, a switch in said shunt circuit, a switch in said main circuit, means for automatically opening said main circuit switch consequent to closing said shunt circuit switch and means for opening said shunt circuit switch and closing said main circuit switch when a current no longer exists, in said shunt circuit.

3. In combination with an inductive resistance connected in a main circuit, a switch in said main circuit a resistance element connected in shunt with said inductive resistance, a switch in said shunt circuit, means for closing said shunt circuit switch and simultaneously opening said main circuit switch, a coil in series with said inductive resistance and said shunt circuit for holding said shunt circuit switch closed and means for opening said shunt circuit switch when a current no longer exists in its circuit.

4:. In combination with an inductive resistance connected in a main circuit, a resistance element connected in shunt with said inductive resistance, a switch in said shunt circuit, a switch in said main circuit, means for automatically opening said main circuit switch consequent to closing said shunt circuit switch and means for sending a current through said inductive resistance in reverse direction to the main circuit current when said shunt circuit switch is closed.

5. In combination with an inductive resistance connected in a main circuit, three auxiliary circuits means whereby the main circuit being bI'OliGIl, one of said auxiliary circuits forms a closed circuit with said inductive resistance and means whereby the main circuit being broken the other two auxiliary circuits cooperate in supplying said inductive resistance with a current in reverse direction to the main circuit current.

6. In combination with an inductive resistance connected in a main circuit, three auxiliary circuits, a resistance element in each of said auxiliary circuits, means whereby the main circuit being broken, one of said .auxiliary circuits forms a closed circuit with said inductive resistance and means whereby the main circuit being broken, the other two auxil ar circuits cooperate in supplying said in uctive resistance with a current in reverse direction to the main circuit current.

7. In combination with an inductive resistance connected in a main circuit, a.

switch in said main circuit, a second switch 1n said main circuit, a shunt circuit in connection with said main circuit and bridging said inductive resistance and one of said switches, a second shunt circuit in connection with said main circuit and bridging said inductive resistance and the other of said switches, a switch in each of said shunt circuits, and means for opening said main circuit switches and closing said shunt circuit switches, whereby a current in reverse direction to said main circuit current is led to said inductive resistance through one of said shunt circuits and led away through the other of said shunt circuits.

8. In combination with an inductive resistance connected in a main circuit, a switch in said main circuit, a second switch in said main circuit, a shunt circuit in connection with said main circuit and bridging said inductive resistance and one of said switches, a second shunt circuit in connection with said main circuit and bridging said inductive resistance and the other of said switches, a switch in each of said shunt circuits, a resistance element in one or both of said shunt circuits, and means for opening said main circuit switches and closing said shunt circuit switches whereby a current in reverse direction to said main circuit current is led to said inductive resistance through one of said shunt circuits and led away through the other of said shunt circuits.

9. In combination with an inductive resistance connected in a main circuit, a switch in said main circuit, a second switch in said main circuit, a shunt circuit in connection with said main circuit and bridging said inductive resistance and one of said switches, a second shunt circuit in. connection with said main circuit and bridging said inductive resistance and the other of said switches a switch in each of said shunt circuits, a coii in said main circuit for holding one of said main circuit switches, a coil excited from said main circuit for operating the other of said main circuit switches and the shunt circuit switches, a switch for controlling the excitation of said coil whereby said operatin coil being excited, the main circuit switc under its control is opened, said shunt circuit switches are closed, and said holding coil is tie-energized, allowing said other main circuit switch to open, whereby a current .in opposite direction to the main circuit current is supplied to said inductive resist- 20 ance through said shunt circuits.

10. In combination with an inductive resistance, a source of current, three auxiliary circuits, a control lever, means whereby said control lever bein moved in one direction, connection is me e between said inductive resistance and said source of current, and means whereby said control lever being moved in the opposite direction said connection is broken,one of said auxiliary circuits is connected in shunt with said inductive resistance, and the other two auxiliary circuits are brought into cooperation with said source of current and said inductive resistance whereby a current in a direction reverse to that of said source of current is supplied to said inductive resistance.

The foregoing specification signed at Essen, Germany, this 30th day of August,

T 11 PFRETzscu-NER. 

